donaldG2

This plugin uses the Repeater field of Advanced Custom Fields to add options for a Credit and Credit Link on each item in your Media Library. Currently this will only correlate and display for IMAGES on the front end. This does not support credits for .pdf files, .swf files, .doc files, etc.
Requires either <a href="http://www.advancedcustomfields.com/pro/" rel="nofollow ugc">Advanced Custom Fields Pro</a> or the <a href="http://www.advancedcustomfields.com/" rel="nofollow ugc">free version of ACF</a> with the <a href="http://www.advancedcustomfields.com/add-ons/repeater-field/" rel="nofollow ugc">Repeater Field</a> add-on.
I suggest using ACF Pro with this plugin.
ACF Fields are exported as a json file (for ACF Pro) in the ‘acf_exports’ directory of this plugin. 
ACF Pro allows you to import that json file if for some reason you’re having trouble getting the fields to load.
If you’re a developer there are functions available to you (see: <a href="http://dongaines.com/acf-media-credit/" rel="nofollow ugc">dongaines.com/acf-media-credit</a>)
In the ‘/inc/’ directory the fields have been exported as PHP to work w/ ACF Pro or ACF free
<h3>Functions</h3>
There are a handful of functions available for your use and there is more explanation given to them at <a href="http://dongaines.com/acf-media-credit/" rel="nofollow ugc">dongaines.com/acf-media-credit</a>. The functions available: 
 the_post_thumbnail_media_credit(); //does not require an attachment id 
 the_media_credit_html($attachment_id); //returns 
 the_media_credit($attachment_id); //echos the_media_credit_html(); 
 the_plain_media_credit($attachment_id); //outputs the most basic markup 
 print_r(get_media_credit($attachment_id)); //helpful for debugging
For images with a caption I’m filtering the caption shortcode, please do the same if you need to make a change: <code>add_filter( 'img_caption_shortcode', 'your_function_name', 10, 3 );</code>
Added filters: 
 add_filter(‘acf_media_credit_base_output’, ‘your_function_name’); //your_function_name($image_credit) 
 add_filter(‘acf_media_credit_div_class’, ‘your_function_name’); //your_function_name($media_credit_div_class)

ACF Media Credit

Adds an option to create as many media credit fields as needed for an image.

add-ons.org

Repeater Fields for WPForms

My author

Good

The Repeater Fields for WPForms allow you to create one or more sets of fields that can be repeated.

ACF Media Credit vs Repeater Fields for WPForms